1. Field of the Invention
This invention relates to a sunlight-into-energy conversion apparatus for simultaneously converting sunlight energy into thermal and electrical energy, and more particularly to an apparatus of this kind incorporating a heat collecting plate contained in a cubiform container and fitted with solar cells thereon and a heating medium tube on its under surface so as to convert sunlight into electricity and heat efficiently without waste.
2. Description of the Prior Art
An apparatus for converting sunlight into electricity and heat was disclosed, for instance, in the Japanese Official Patent Gazette No. 48227, 1980. The disadvantage is that the use of heating medium tubes and solar cells in a vacuum tube makes the apparatus of that type extremely costly; besides, a number of converters required for obtaining a large quantity of electricity and calories make the apparatus further costly because the quantity of electricity and calories obtainable from a single converter is quite small.
Accordingly, it appears feasible to mount solar cells on the surface of the heat collecting plate (1) of the well known natural circulation type heat collector (A) disclosed in the Official Utility Model Gazette No. 236543, 1981 as shown in FIG. 1, wherein a light-permeable glass plate (3) is installed to cover an upside opening made in a cubiform container (2) constructed of an iron plate and the like by fastening the glass plate to the container with an organic sealant such as a silicon compound or by mechanically fixing them.
However, since the thermal expansivity of the glass plate (3) is by far different from that of the cubiform container (2), thermal strain is produced. For this reason, the portion of the glass connected to the cubiform container (2) is damaged and thus unable to make the inside of the container (2) completely airtight. As a result, moisture allowed to permeate and condense therein causes the electrode of the solar cell to oxidize and ultimately the solar cell itself to deteriorate. This problem has made it impossible to contain solar cells in a cubiform heat collector, though such a cubiform container is, in view of cost reduction, advantageous as an enclosure for installing the cells.